Water-based fluorine-containing paint

ABSTRACT

The invention provides a first water-based fluorine-containing paint including a water-based emulsion containing a fluorine-containing copolymer dispersed therein, and 1-50 parts by weight of a hardener per 100 parts by weight of the copolymer. The copolymer is prepared by copolymerizing 30-65 mol % of a fluoroolefin, 14-69 mol % of a copolymerizable vinyl-containing compound, and 1-30 mol % of a hydroxyl-containing compound and/or a polymerizable carboxyl-containing compound. The hardener is prepared by mixing 1 part by weight of a self-emulsifiable polyisocyanate with 0.01-1 part by weight of a compound containing in the molecule an oxyethylene unit and an alkoxysilyl group. When mixed with the emulsion, the hardener becomes well dispersed therein. The invention further provides a second water-based fluorine-containing paint including a water-based emulsion containing a fluorine-containing copolymer dispersed therein, and a hardener which is a compound containing in the molecule at least two hydrazino groups. The fluorine-containing copolymer is prepared by emulsion polymerization of 30-65 mol % of a fluoroolefin, 0.1-20 mol % of a polymerizable unsaturated carboxylic acid, 1-30 mol % of a polymerizable acetoacetylallyl compound, and 20-65 mol % of one of a vinyl ester and a vinyl ether. The second paint does not cure at ambient temperature, even after the hardener has been added thereto, and thus is usable as a one-package paint.

BACKGROUND OF THE INVENTION

The present invention relates to a water-based fluorine-containing paintwhich is curable at ambient temperature.

Fluororesins are generally excellent in chemical resistance, weatherresistance and heat resistance, and in view of these favorableproperties the use of fluororesin based paints is increasing in variousfields.

As a fluororesin suitable for solvent-thinned paints, U.S. Pat. No.4,631,326 discloses a fluorine-containing copolymer comprisingchlorotrifluoroethylene, a vinyl or isopropenyl ester of fatty acid anda hydroxyl-containing allyl ether, This allyl ether provides afunctional group to the copolymer for curing the copolymer. JapanesePatent Unexamined Publication No. 57-34107 discloses afluorine-containing copolymer which is curable at ambient temperatureand comprises a fluoroolefin, cyclohexylvinyl ether, an alkylvinylether, and an hydroxyalkylvinyl ether. This hydroxylalkylvinyl etherprovides a functional group to the copolymer for curing the copolymer.

Fluororesin-containing solvent-thinned paints are widely used as weatherresistant paints in the fields of architecture, automobile and chemicalengineering. Furthermore, in view of the environmental protection,fluororesin-containing water-based paints, powder paints, and high-solidpaints have been developed, too. Each fluororesin for these paintscomprises a fluorocarbon as a rain component, such aschlorotrifluoroethylene, tetrafluoroethylene or vinylidene fluoride, anda copolymerizing hydrocarbon monomer such as vinyl ester or vinyl ether,which is added for the purpose of increasing solubility of thefluororesin. It has been difficult to provide the above-mentionedfluororesin-containing water-based paint with a functional group forforming a cross-linking structure, Therefore, a so-called lacquer-typewater-based paint in the form of emulsion of a high-molecular compoundprepared by emulsion polymerization was used in many cases of thecoating step. In view of this, a hardener for forming a cross-linkingstructure at ambient temperature was developed, such as an oxazolinecompound or a self-emulsifiable polyisocyanate. The hardening action bythe polyisocyanate, however, tends to terminate due to the reaction ofisocyanate group with water (dispersion medium). Thus, it has beennecessary to add the polyisocyanate to vehicle, immediately before thecoating step, in view of pot life of the paint. However, a conventionalself-emulsifiable polyisocyanate is insufficient in dispersibility inwater. Thus, it has been difficult, particularly in a coating site, touniformly finely disperse the polyisocyanate in water. With this, acoated film becomes insufficient in water resistance, weatherresistance, stain resistance and the like.

In contrast to the above-mentioned two-package type paints, there havebeen proposed one-package type paints in the field of water-basedacrylic-ester paints. For example, Japanese Patent UnexaminedPublication No. 57-3850 discloses a water-based disperse systemcontaining, as a disperse phase, carbonyl-containing copolymerparticles. Japanese Patent unexamined Publication No. 4-81447 disclosesa water-based emulsion composition which is a mixture of aself-emulsifiable polyurethane and a water-based acrylic-resin emulsionwhich is cross-linkable at ambient temperature.

Similar to the above-mentioned acrylic ester paint, there has been arecent demand for a water-based fluorine-containing paint which isone-package type and capable of providing a coated film superior inwater resistance, weather resistance, stain resistance and the like.

SUMMARY OF THE INVENTION

It is therefore an object of the first aspect of the present inventionto provide a water-based fluorine-containing paint containing a hardenerwell dispersed in the paint.

It is therefore an object of the second aspect of the present inventionto provide a water-based fluorine-containing paint which is chemicallystable at ambient temperature, even after the hardener is added thereto,and this usable as a one-package type paint.

According to a first aspect of the present invention, there is provideda first water-based fluorine-containing paint comprising:

a water-based emulsion containing water as a dispersion medium and afluorine-containing copolymer as a disperse phase, saidfluorine-containing copolymer being prepared by copolymerizing 30-65 mol% of a fluoroolefin, 14-69 mol % of a copolymerizable vinyl-containingcompound, and 1-30 mol % of a first compound which is at least one of ahydroxyl-containing compound and a polymerizable carboxyl-containingcompound; and

1-50 parts by weight of a hardener per 100 parts by weight of saidfluorine-containing copolymer, said hardener being prepared by mixing aself-emulsifiable polyisocyanate with 0.01-1 part by weight, per part byweight of said polyisocyanate, of a second compound containing in themolecule an oxyethylene unit and an alkoxysilyl group.

According to the first aspect of the present invention, the inventorshave unexpectedly found that, when the second compound is mixed with aself-emulsifiable polyisocyanate, the polyisocyanate becomes welldispersed in water contained in the first paint. That is, the hardenerwhich is a mixture of the polyisocyanate and the second compound is welldispersed in the paint. With this, a coated film prepared by applyingthe first paint becomes homogeneous and exhibits a good waterresistance, a good stain resistance and a good weather resistance, whichare directly derived from a fluororesin contained in the first paint.The first paint can be easily prepared by mixing together thewater-based emulsion and the hardener at a coating site, because thehardener is well mixed with and well dispersed in the emulsion.

According to a second aspect of the present invention, there is provideda second water-based fluorine-containing paint comprising:

a water-based emulsion containing water as a dispersion medium and afluorine-containing copolymer as a disperse phase, saidfluorine-containing copolymer being prepared by emulsion polymerizationof 30-65 mol % of a fluoroolefin, 0.1-20 mol % of a polymerizableunsaturated carboxylic acid represented by the general formula (1), 1-30mol % of a polymerizable allyl compound represented by the generalformula (2), and 20-65 mol % of a first compound which is one of a vinylester and a vinyl ether; and

a hardener which is a second compound containing in the molecule atleast two hydrazino groups,

    CH.sub.2 ═CH--(CH.sub.2).sub.n --COOH                  (1)

where n is an integer from 7 to 9, ##STR1## where R represents--(AO)_(n) -- in which A is an alkylene group having a carbon atomnumber from 2 to 4, and n is an integer from 0 to 20.

According to the second aspect of the present invention, the inventorsunexpectedly found that the second paint does not cure until its use andthus can be stably stored until its use, even after the above-mentionedspecial hardener has been mixed with the water-based emulsion.Therefore, the second paint can be used as an one-package paint. Afterthe second paint is applied to a substrate to form a coated filmthereon, cross-linking of the second paint proceeds at ambienttemperature. The thus formed coated film is superior in waterresistance, weather resistance, stain resistance and the like,Furthermore, the second paint does not contain an organic solvent. Thisis an advantage from a view point of environment.

DESCRIPTION Of THE PREFERRED EMBODIMENTS

In the following, a water-based fluorine-containing paint according tothe first and second aspects of the present invention will be describedin detail.

According to the first and second aspects of the present invention,there is used 30-65 mol % of a fluoroolefin as a monomer for preparingthe fluorine-containing copolymer, based on the total number of moles ofall the monomers. The mol percentages of the other monomers are alsodefined in the same manner as this fluoroolefin. Examples of thefluoroolefin are chlorotrifluoroethylene, tetrafluoroethylene,hexafluoropropene, hexafluoroisobutene, vinylidene fluoride,trifluoroethylene, and vinyl fluoride. If it is less than 30 mol %, acoated film becomes inferior in weather resistance. If it is greaterthan 65 mol %, the fluorine-containing copolymer does not well dispersein water.

According to the first aspect of the present invention, there is used14-69 mol % of a copolymerizable vinyl-containing compound for preparingthe fluorine-containing copolymer. If it is less than 14 mol %, thecopolymerization rate is lowered too much. If it is greater than 69 mol%, the fluorine content of the copolymer becomes too small. Thevinyl-containing compound is not limited to a particular one. Preferableexamples of this compound are vinyl esters, vinyl ethers, and allylethers. Of vinyl esters, polymerizable ester compounds each havingcarbonyl group in the molecule can be used. Examples of the estercompounds are vinyl acetate, vinyl propionate, vinyl lactate, vinylpivalate, vinyl caproate, vinyl caprylate, vinyl laurate, vinylmyristate, vinyl palmitate, vinyl stearate, neononanoic acid ethenylester, neodecanoic acid ethenyl ester, and vinyl benzoate. As commercialproducts of neononanoic acid ethenyl ester and neodecanoic acid ethenylester, VEOVA-9 and VEOVA-10 made by Showa-Shell Chem. Co. can be cited,respectively. Examples of the vinyl ethers are methyl vinyl ether, ethylvinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether. Examples ofthe allyl ethers are ethylallyl ether, butylallyl ether, benzylallylether, allylglycidyl ether, cyclohexylallyl ether, and allylacetoacetate. Furthermore, a vinyl ether or ally ether, which has apolyalkylene glycol chain such as polyethylene glycol chain orpolypropylene glycol chain, may be used as the vinyl-containingcompound, for the purpose of more easily emulsifying thefluorine-containing copolymer. Still furthermore, an alkoxyvinyl silanecompound such as trimethoxyvinyl silane, triethoxyvinyl silane ordiethoxymethoxyvinyl silane may be used as the vinyl-containingcompound. It is optional to add an olefin such as ethylene, propylene orvinyl chloride to the vinyl-containing compound.

According to the first aspect of the present invention, there is used1-30 mol % of a first compound which is at least one of a polymerizablehydroxyl-containing compound and a polymerizable carboxyl-containingcompound. The first compound is used for cross-linking the first paint.If it is less than 1 mol %, the cross-linking of the first paint becomesinsufficient. With this, the coated film becomes inferior in weatherresistance and water resistance. If it is greater than 30 mol %, thefluorine-containing copolymer becomes too much in hydrophilicity. Withthis, a coated film becomes inferior in water resistance.

According to the first aspect of the present invention, examples of thepolymerizable hydroxyl-containing compound are hydroxyl-containingallylethers, hydroxyl-containing vinyl ethers and crotonic-acid modifiedcompounds. Examples of the hydroxyl-containing allylethers are alkyleneglycol monoallyl ethers such as ethylene glycol monoallyl ether,propylene glycol monoallyl ether, diethylene glycol monoallyl ether,polyethylene glycol nonoallyl ether, and hydroxybutyl allyl ether.Examples of the hydroxyl-containing vinyl ethers are hydroxyalkyl vinylethers such as hydroxymethyl vinyl ether, hydroxyethyl vinyl ether,hydroxybutyl vinyl ether, hydroxypentyl vinyl ether and hydroxyhexylvinyl ether, and polyethylene glycol monovinyl ethers such as diethyleneglycol monovinyl ether. An example of the crotonic-acid modifiedcompounds is hydoxyethyl crotonic acid. Furthermore, glycerol monoallylether and ε-caprolactone-modified allyl ether or vinyl ether, each ofwhich has two hydroxyl groups in the molecule, can be cited as examplesof the hydroxyl-containing compound, too.

According to the first aspect of the present invention, theabove-mentioned polymerizable carboxyl-containing compound is notlimited to a particular one, as long as it has a carboxyl group and apolymerizable double bond in the molecule. Preferable examples of thecarboxyl-containing compound are vinylacetic acid, decenoic acid,10-undecylenic acid, and crotonic acid. Of these, 10-undecylenic acid isparticularly preferable, because 10-undecylenic acid introduced into thefluorine-containing copolymer serves as a reactive emulsifying agent.Therefore, it is possible to reduce the amount of an emulsifying agentused in the preparation of the water-based emulsion. With this, a coatedfilm is further improved in water resistance and weather resistance.

According to the second aspect of the present invention, thepolymerizable unsaturated carboxylic acid represented by the generalformula (1) has a total carbon number from 10 to 12 and consists of onlya straight-chain alkenyl group and carboxyl group. It is considered thatthis carboxylic acid contributes to improve the coated film in weatherresistance, as shown in the aftermentioned Examples 5-10, in spite ofthe fact that this coated film is formed by applying the waterbasedemulsion paint. In other words, it is considered that the carboxylicacid serves as a reactive emulsifying agent, and thus it becomespossible to reduce the amount of the emulsifying agent used in theemulsion polymerization. With this, it also becomes possible to reducethe amount of the remaining emulsifying agent in the paint, and thus itbecomes possible to suppress the decline in weather resistance of thecoated film. The carboxylic acid, serving as an emulsifying agent,exists at the interface between particles of the disperse phase andwater (dispersion medium), and thus is always in contact with water.However, the carboxylic acid is at this interface in a chemically stablemanner, due to that it does not have a hydrolyzable structure in themolecule. It is considered that this characteristic of the carboxylicacid contributes to improve the emulsion stability in the polymerizationreaction, the stability of the water-based emulsion during storagethereof and the mechanical stability of the same, the stability of thewater-based paint during storage thereof, and weather resistance of thecoated film.

According to the second aspect of the present invention, it is importantthat n is from 7 to 9 in the general formula (1) representing thepolymerizable unsaturated carboxylic acid. If n is less than 7, thecarboxylic acid tends to be dissolved in water and thus does not serveas an emulsifying agent. Furthermore, the yield of polymerization isreduced. If n is greater than 9, the carboxylic acid becomes too high inhydrophobicity. With this, the emulsification action of the carboxylicacid is substantially lowered. The amount of the carboxylic acid is from0.1 to 20 mol % and preferably from 3 to 10 mol %. If it is less than0.1 mol %, the carboxylic acid does not effectively function as areactive emulsifying agent. If it is greater than 20 mol %, the coatedfilm becomes inferior in water resistance. Examples of the carboxylicacid are 9-decenoic acid, 10-undecylenic acid, 11-dodecylenic acid. Ofthese, 10-undecylenic acid is particularly preferably used.

According to the second aspect of the invention, the polymerizable allylcompound represented by the above-described general formula (2) iscopolymerized with the other monomers for introducing acetoacetyl groupinto the fluorine-containing copolymer. This acetoacetyl group servesfor cross-linking the copolymer. "AO" represented by "R" in the generalformula (2) is an oxyalkylene group, and its nonlimitative four examplesare as follows.

    (CH.sub.2 --CH.sub.2 --O)--

    (CH.sub.2 --CH.sub.2 --CH.sub.2 --O)-- ##STR2##

    --(CH.sub.2 --CH.sub.2 --CH.sub.2 --CH.sub.2 --O)--

In the general formula (2), "(AO)_(n) " may be a single oxyalkylenegroup or a mixture of at least two oxyalkylene groups. If "n" in thegeneral formula (2) is greater than 20, the coated film becomes inferiorin water resistance. The method of producing the polymerizable allylcompound is not limited to a particular one. For example, thepolymerizable ally compound is prepared by reacting ahydroxyl-containing allyl compound with diketene. In this reaction, thepolymerizable allyl compound is obtained with a high yield by mixing andstirring these compounds together at room temperature or at atemperature not higher than 80° C. An example of commercial product ofthe polymerizable allyl compound is allyl acetoacetate. It is consideredthat the polymerizable allyl compound tends to be concentrated at theouter surface of particles of the disperse phase of the water-basedemulsion under a condition that the allyl compound is coexistent withthe polymerizable unsaturated carboxylic acid. With this, the hardeningreaction is considered to proceed effectively. The amount of thepolymerizable allyl compound is from 1 to 30 mol % and preferably from 2to 10 mol %. If it is less than 1 mol %, the degree of cross-linking ofthe coated film becomes insufficient. If it is greater than 30 mol %,the fluorine-containing copolymer itself becomes inferior in weatherresistance. Furthermore, the coated film becomes inferior in strength,because it is necessary to increase the amount of hardener to a certainlevel in accordance with the amount of the allyl compound.

According to the second aspect of the present invention, the firstcompound which is one of a vinyl ester and a vinyl ether is notparticularly limited. Examples of this vinyl ester are polymerizableester compounds each having carbonyl group in the molecule, such asthose examples of the vinyl ester according to the first aspect of thepresent invention and vinylcyclohexyl acid. Examples of the vinyl etherare those examples of the copolymerizable vinyl ether of the firstaspect of the present invention and those examples of thehydroxyl-containing polymerizable vinyl ether thereof. Furthermore, avinyl ether having a polyalkylene glycol chain may be used as the vinylether, as is above-described in accordance with the first aspect of thepresent invention. It is also optional to add, to the first compound, analkoxyvinyl-silane compound, a hydroxyl-containing allyl ether, ahydroxyl-containing crotonic acid modified compound, and/or a glycerolmonoallyl ether or ε-caprolactone modified allyl ether, which has twohydroxyls in the molecule, as is above-described in accordance with thefirst aspect of the present invention. The amount of the first compoundis from 20 to 65 mol % and preferably from 30 to 50 mol %. If it is lessthan 20 mol %, the polymerization rate becomes too low. If it is greaterthan 65 mol %, the coated film becomes inferior in weather resistancedue to that the fluorine content of the copolymer becomes too low.

According to the second aspect of the present invention, vinyl esterresin, acrylic resin and/or methacrylic resin may be previously mixedwith the first compound, prior to the copolymerization, and can becopolymerized. The addition of these resins contributes to improve thecoated film in gloss and in stain resistance. In particular, the coatedfilm is improved in easiness to wipe off stains thereon, by adding atleast one of these resins, which has a glass transition point not lowerthan 30° C. Such resin contributes to prevent the coated film fromhaving stains thereon in outdoor exposure test. These resins are notparticularly limited as long as these are dissolved in the firstcompound and compatible with the fluorine-containing copolymer.

According to the second aspect of the present invention, it is optionalto add an olefin such as ethylene, propylene or vinyl chloride to theother monomers, for improving the fluorine-containing copolymer incharacteristics.

According to the first aspect of the present invention, thefluorine-containing copolymer is obtained by copolymerizing theabove-mentioned essential three kinds of monomers together, in thepresence of a commonly used radical polymerization initiator. The mannerof the copolymerization reaction is not particularly limited. Forexample, the object is accomplished by solution polymerization,suspension polymerization, or emulsion polymerization. Of these,emulsion polymerization is particularly preferable, because it providesthe fluorine-containing copolymer dispersed in the water-based emulsion.

According to the first aspect of the present invention, an anion ornonion emulsifying agent can be used as an emulsifying agent in theemulsion polymerization. Examples of the anion emulsifying agent arealkylbenzenesulfonate, alkylsulfate, polyoxyethylenealkylphenolsulfate,styrenesulfonate, vinylsulfate, and derivatives of these. These saltsmay be produced by the interaction of the acids (e.g., alkylsulfuricacid) and bases (e.g., alkali metal hydroxides and volatile bases).Examples of the volatile bases are ammonia and triethylamine. Examplesof the above-mentioned nonion emulsifying agent arepolyoxyethylenealkylphenolethers, polyoxyethylenealkylethers,polyoxyethylene higher fatty acid esters, ethyleneoxide-propyleneoxideblock copolymers, fluoroalkylcarboxylates, and fluoroalkylsulfates.

In the present invention, the amount of the emulsifying agent variesdepending on composition of the monomers and on the concentration of themonomers in water. In fact, according to the first aspect of the presentinvention, it is preferable to use 0.5-10 parts by weight of theemulsifying agent per 100 parts by weight of the total of all themonomers. If it is less than 0.5 parts by weight, the monomers may notsufficiently disperse in the water phase. If it is greater than 10 partsby weight, the coated film may become inferior in water resistance andweather resistance. According to the second aspect of the presentinvention, it is preferable to use less than 5 parts by weight of theemulsifying agent per 100 parts by weight of the total of all themonomers. If it is greater than 5 parts by weight, the coated film maybecome inferior in water resistance and weather resistance.

According to the second aspect of the present invention, thepolymerizable unsaturated carboxylic acid serves as an emulsifyingagent, as stated above. Therefore, an emulsifying agent may be omitted,or its amount may substantially be reduced. The above-exemplified anionor nonion emulsifying agent as to the first aspect of the presentinvention may be used together with the polymerizable unsaturatedcarboxylic acid.

According to the first and second aspects of the present invention, aradical polymerization initiator usable in the emulsion polymerizationfor preparing the fluorine-containing copolymer is not limited to aparticular type, as long as it is usable in a common emulsionpolymerization, A water-soluble initiator is particularly preferablyused. Examples of water-soluble initiator are inorganic peroxides suchas hydrogen peroxide, organic peroxides such as cumene hydroperoxide,benzoyl peroxide, t-butyl hydroperoxide, disuccinic acid peroxide,diglutaric acid peroxide, persulfates such as ammonium persulfate,potassium persulfate and sodium persulfate, and azo-initiators such ashydrochloride of azobisisobutylamidine, azobisisobutyronitrile andazobiscyanovaleric acid. Further examples of water-soluble initiator areredox initiators which are combinations of the above-exemplifiedinitiators and reducing agents such as sodium sulfite, sodiumthiosulfate, sodium bisulfite, sodium metabisulfite, sodiumbithiosulfate, formaldehyde sodium sulfoxylate and reducing sugar. Tothe redox initiator, it is optional to add a small amount of iron,ferrous salt, silver sulfate, copper sulfate and the like.

According to the first and second aspects of the present invention, theamount of the radical polymerization initiator varies depending on itstype, the concentration of the monomers in the water-based emulsion, thepolymerization temperature and the like, and is preferably from 0.05 to5 parts by weight per 100 parts by weight of the total of all themonomers. The radical polymerization initiator may be added at one timeor several times.

According to the first and second aspects of the present invention, theamount of water used in the emulsion polymerization varies depending onthe monomer composition, the emulsifying agent concentration and thelike, and this water may be from 50 to 400 parts by weight andparticularly preferably from 70 to 150 parts by weight per 100 parts byweight of the total of all the monomers. If it is less than 50 parts,the particle diameter of disperse phase in the emulsion may become toolarge. With this, the emulsion may not be chemically stable duringstorage, or the time until the coated film sets to touch may become toolong. That is; at this time, when the coated film is touched withfingers, the fingers are not stained thereby. If it is greater than 400parts, the solid matter concentration of the water-based emulsion maybecome too low. The solid matter concentration of the emulsion may beadjusted by adding water to or removing water from the emulsionpolymerization product.

According to the first and second aspects of the present invention, thetemperature of the copolymerization reaction varies according to thetype of the radical polymerization initiator, but usually is within arange from 0° to 150° C.

According to the first aspect of the present invention, the water-basedemulsion may be obtained by dispersing, in water, a varnish of thefluorine-containing copolymer obtained by suspension polymerization orsolution polymerization where a common organic solvent is used. Themanner of dispersing the varnish in water is not particularly limited.For example, a solution of the fluorine-containing copolymer dissolvedin a non-aqueous organic solvent may be introduced into water in thepresence of an emulsifying agent or without using the agent. Thenon-aqueous organic solvent is not particularly limited, as long as itis usable as a common non-aqueous thinner for paint. As this solvent,toluene, xylene, butyl acetate, ethyl acetate, propylene glycol methylacetate, alkyl silicate, or the like is particularly preferably used.This alkyl silicate is referred to as tetraalkoxysilane or itscondensates Examples of the alkyl silicate are tetramethoxysilane,tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane,tetra-n-butoxysilane, tetra-2-methoxyethoxysilane,tetra-2-ethylhexyloxysilane, and condensates of these. Variouscommercial alkyl silicates are available. These silicates are preparedby at first partially hydrolyzing tetraalkoxysilane and then condensingthe partial hydrolysate, and are different in condensation degree,structure, and the type of alkoxyl group. Examples of these silicatesare M SILICATE 51, ETHYLSILICATE 40, and ETHYLSILICATE 45, all of whichare trade names of TAXA CHEMICAL INDUSTRY CO. It is possible to use analkyl silicate having a silica component concentration up to 57 wt %, byfurther hydrolyzing the commercial alkyl silicate and thus by increasingthe silica component concentration thereof. It is not preferable to usean alkyl silicate which is partially hydrolyzed but not condensedenough, because such alkyl silicate is hydrophilic or soluble in waterand thus is not well dispersed in the water-based emulsion.

According to the first aspect of the present invention, the solid matterconcentration of the water-based emulsion is preferably from 10 to 70 wt%. If it is lower than 10 wt %, the paint volume may become too large.This is inconvenient from a view point of storing or transporting thepaint. If it is higher than 70 wt %, the water-based emulsion may becometoo high in viscosity. With this, it becomes difficult to smoothly applythe paint to a substrate.

In the first aspect of the present invention, as stated above, thehardener is prepared by uniformly mixing a self-emulsifiablepolyisocyanate with 0.01-1 part by weight, per part by weight of thepolyisocyanate, of the second compound containing in the molecule anoxyethylene unit and an alkoxysilyl group. If the second compound isless than 0.01 parts by weight, the polyisocyanate is not sufficientlydispersed in water. With this, cross-linking of the coated film is notuniformly distributed. Thus, the coated film becomes inferior in waterresistance, weather resistance, stain resistance and the like. If thesecond compound is greater than 1 part by weight, the alkoxysilyl groupcontent of the paint becomes too high. With this, cracks tend to occurin the coated film in the course of cure thereof.

In the first aspect of the present invention, the self-emulsifiablepolyisocyanate is not limited to a particular type, as long as it has askeleton of polyisocyanate and a hydrophilic group such as oxyethylenegroup. Examples of such skeleton are hexamethylene diisocyanate,tolylene diisocyanate, xylene diisocyanate, isophorone diisocyanate,diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate,hydrogenated xylene diisocyanate, and hydrogenated diphenylmethanediisocyanate. Examples of commercial products of the self-emulsifiablepolyisocyanate are BAYHYD-UR TPLS-2032 (trade name) of Sumitomo BayerUrethane Co. and DC-3900, DC-3901 and DC-3712 (trade names) of NipponPolyurethane Industry Co. Each of these products contains ioxyethylenegroup in the molecule.

In the first aspect of the present invention, the second compound to bemixed with the self-emulsifiable polyisocyanate preferably has anoxyethylene repeating unit number from 1 to 20. If the second compounddoes not have an oxyethylene unit, it becomes difficult to achieveself-emulsification of the second compound. If the oxyethylene repeatingunit number exceeds 20, the second compound may be dissolved in water.Examples of alkoxysilyl group contained in the second compound'smolecule are methyldiethoxysilyl group, triethoxysilyl group,methyldimethoxysilyl group, trimethoxysilyl group, tripropoxysilylgroup, triisopropoxysilyl group, tris(β-methoxy)silyl group,tributoxysilyl group, tri(2-methoxyethyl)silyl group, andtri(2-ethylhexyloxy)silyl group.

In the first aspect of the present invention, the method of producingthe second compound is not limited to a particular one. The secondcompound can be obtained, for example, by reacting a compound containinga reactive group and an alkoxysilyl group, with a polyoxyethylenederivative containing a reactive group. In this reaction, there occursan addition reaction between hydroxyl and isocyanate group, a couplingreaction between epoxy or halogeno group and amino group, or the like.As another example, the second compound can be obtained by at firstvinylating terminal(s) of a polyoxyethylene having hydroxyl group(s) atone or both of the terminals thereof by a metal alcoholate, ahologenated allyl compound or the like, then silylating the terminal(s)by trichlorosilane, and then alkoxysilylating the terminal(s) by a metalalcoholate. It is particularly preferable to prepare the second compoundby reacting a polyoxyethylene derivative having anactive-hydrogen-containing reactive group (e.g., hydroxyl, carboxyl,amino and mercapto groups) with a compound containing isocyanate group(--N═C═O) and alkoxysilyl group, because this reaction does not requirecomplicated reaction steps. An example of the compound to be reactedwith the polyoxyethylene derivative is an alkoxysilane represented bythe general formula (3),

    OCN(CH.sub.2).sub.3 SiX.sub.n Y.sub.(3-n)                  ( 3)

where Y is hydrogen or a hydrocarbon group having a carbon atom numberfrom 1 to 8, x is an alkoxyl having a carbon atom number from 1 to 3,and n is an integer from 1 to 3. Preferable examples of thisalkoxysilane are γ-isocyanatepropylmethyldiethoxysilane,γ-isocyanatepropyltriethoxysilane,γ-isocyanatepropylmethyldimethoxysilane,γ-isocyanatepropyltrimethoxysilane. Exemplary commercial products of thealkoxysilane are Y-5187 (trade name) having trimethoxysilyl group andY-9030 (trade name) having triethoxysilyl group, both of which are madeby Nippon Unicar Co.

In the first aspect of the present invention, it is preferable that theabove-mentioned polyoxyethylene derivative has in the molecule theoxyethylene unit and at least one reactive hydroxyl. It is particularlypreferable that the polyoxyethylene derivative has an oxyethylenerepeating unit number from 1 to 20. Examples of the polyoxyethylenederivative are oxyethylene, polyoxyethylene,polyoxyethylenealkylarylether, polyoxyethylenealkylether,polyoxyethylenealkylester, polyethylenealkylamine,polyoxyethylenearylether, polyoxyethylenearylester, sorbitan fatty acidesters, polyalcohols (e.g., glycerol) modified by oxyethylene,oxyethylene-modified silicones. The polyoxyethylene chain of theseexamples may be copolymerized with another oxyalkylene such asoxypropene or oxytetramethylene. This copolymerization may be randomcopolymerization or block copolymerization.

In the first aspect of the present invention, it is assumed that thesecond compound is provided with self-emulsification property due toamphipathic property thereof. That is, the second compound hashydrophilicity caused by the polyoxyethylene segment thereof andhydrophobicity caused by the alkoxysilyl segment thereof. It isconsidered that the polyoxyethylene segment improves compatibilitybetween the second compound and the self-emulsifiable polyisocyanate andthus that this polyisocyanate is stably self-emulisified. Thealkoxysilyl segment of the second compound is hydrolyzed and thencross-linked. This characteristic of the alkoxysilyl segment isconsidered to improve the coated film in water resistance and stainresistance.

In the first aspect of the present invention, at least one otheroptional compound may be added to the hardener, preferably in an amountnot higher than 30 wt % of the harder. Examples of this optionalcompound are common polyisocyanates (i.e., non-self-emulsifiablepolyisocyanates) for improving cross-linking of the first paint, organicsolvents and oligomers for lowering viscosity of the hardener, variousemulsifying agents for assisting in self-emulsification of theself-emulsifiable polyisocyanate, alkylsilicates for improving hardnessand stain resistance of the coated film, and water-soluble aminecatalysts for accelerating cross-linking of the first paint. Thewater-soluble amine catalyst may be added to the water-based emulsionand the hardener prior to mixing or these, or may be added to themixture of these. The amount of the amine catalyst is preferably notgreater than 3 parts by weight per 100 parts by weight of thefluorine-containing copolymer contained in the water-based emulsion. Asto the amine catalyst, it is preferable to use an amine catalyst whichis low in catalytic action for catalyzing the reaction of isocyanategroup of the hardener with water and which effectively catalyzesHydrolysis of alkoxysilyl group of the second compound. Examples of theamine catalyst are N,N,N',N'-tetramethyldiamino compounds such asN,N,N',N'-tetramethyldiaminoethane, N,N,N',N'-tetramethyldiaminohexaneand N,N,N',N'-tetramethyldiamino-butane, N-methylmorpholine,N-ethylmorpholine, N-methyl-piperazine, N,N'-dimethylpiperazine,N,N'-dimethylbenzyl-amine, and N,N'-dimethyldodecylamine. Of these,N,N,N',N'-tetramethyldiamino compounds are particularly preferable inview of characteristics of the coated film surface.

In the first aspect of the present invention, as stated above, thehardener is in an amount from 1 to 50 parts by weight per 100 parts byweight of the fluorine-containing copolymer of the water-based emulsion.If it is less than 1 part by weight, the degree of cross-linking of thecoated film becomes insufficient. With this, the coated film becomessubstantially inferior in water resistance and stain resistance. If itis greater than 50 parts my weight, the coated film becomes inferior inweather resistance.

In the first aspect of the present invention, the first paint may beprepared by mixing the water-based emulsion with the hardener which hasbeen previously emulsified in water, or with the hardener itself.

According to the second aspect of the present invention, theabove-mentioned second compound containing in the molecule at least twohydrazino groups (--NHNH₂) is used as a hardener to be mixed with thewater-based emulsion. With this, the second paint can be used as aone-package type paint which is crosslinkable at ambient temperature. Itis assumed that cross-linking proceeds by dehydration between thehydrazino group and the functional group of the polymerizable allycompound. In other words, the second paint is chemically stable atambient temperature, even after the hardener has been added to thewater-based emulsion, and cross-linking does not proceed in water.However, as water evaporates from the coated film, dehydration betweenthe acetoacetyl group and the hydrazino group proceeds, and therebycross-linking proceeds to harden the coated film.

According to the second aspect of the present invention, examples of thesecond compound as a hardener are dicarboxylic acid dihydrazides eachhaving a carbon atom number from 2 to 10, such as oxalic aciddihydrazide, malonic acid dihydrazide, succinic acid dihydrazide,sebacic acid dihydrazide, adipic acid dihydrazide, glutaric aciddihydrazide, maleic acid dihydrazide and fumaric acid dihydrazide,water-soluble fatty acid dihydrazides such as ethylene-1,2-dihydrazide,propylene-1,3-dihydrazide and butylene-1,4-dihydrazide, andwater-soluble hydrazino-containing polymers each having a side chaininto which hydrazino group has been introduced by polymerizing ahydrazino-containing vinyl compound or by copolymerizing this vinylcompound with another monomer. The second compound is easily dissolvedin water by heating. The thus prepared aqueous solution of the secondcompound can be well mixed with the water-based emulsion. The amount ofthe second compound is preferably from 1 to 30 parts by weight and morepreferably from 2 to 15 parts by weight, per 100 parts by weight of thefluorine-containing copolymer. If it is less than 1 part by weight,cross-linking may not sufficiently proceed in the coated film. If it isgreater than 30 parts by weight, the coated film may become inferior instrength.

In the first and second aspects of the present invention, it is optionalto add other additives to the disperse phase or to water (dispersionmedium) of the paint, such as thickener, coalescing agent (e.g., butylcellosolve and butylcarbitol acetate), pigment dispersant (e.g., sodiumtripolyphosphate, sodium polyacrylate and nonion emulsifying agents),dispersion assisting agent, pigment (e.g., titanium white, cadmiumyellow, carbon black, phthalocyanine compounds and azo compounds),defoaming agent, antisetting agent, levelling agent, ultravioletabsorbing agent, light stabilizer, rust preventive agent, and antifungusagent.

The following nonlimitative Examples 1-4 are illustrative of the firstaspect of the present invention, and the following Comparative Examples1-4 are not thereof. In the following, the amount of each monomerexpressed by mol % for preparing the fluorine-containing copolymer isbased on the total number of moles of all the monomers.

EXAMPLE 1

At a first step, a water-based emulsion according to the presentinvention was prepared as follows.

At first, as shown in Table 1, a 2-liter stainless steel autoclaveprovided with an electromagnetic stirrer was charged firstly with amonomer mixture of 71 g (27.0 mol %) of vinyl butyrate (VBu), 43 g (10.0mol %) of neononanoic acid ethenyl ester, VEOVA-9 (V-9), 30 g (10.0 mol%) of hydroxybutyl allyl ether (HBAE) as a first compound, 13 g (3.0 mol%) of 10-undecylenic acid (UA) as a first compound, and 6 g of nonionemulsifying agent, NEWCOL 504 (trade name) of Nippon Nyukazai Co., thenwith an acid-accepting-agent aqueous solution prepared by dissolving 0.3g of sodium carbonate decahydrate in 30 g of ion-exchanged water, thenwith a polymerization initiator aqueous solution prepared by dissolving0.5 g of ammonium persulfate in 30 g of ion-exchanged water, and thenwith 680 g of ion-exchanged water, The thus prepared mixture wasuniformly stirred, Then, the gas atmosphere in the autoclave wasreplaced by nitrogen gas, and this operation was repeated three times,Then, 134 g (50 mol %) of chlorotrifluoroethylene (CTFE) was introducedinto the autoclave. Then, the polymerization reaction was carried out at50° C. for 20 hr to produce a fluorine-containing copolymer A. Then, thereaction liquid was taken out of the autoclave and then concentrated toadjust the solid matter concentration to 50 wt %. Then, pH value of thereaction liquid was adjusted to 8, using 28% aqueous ammonia, thereby toobtain a water-based emulsion A of the fluorine-containing copolymer A.

The thus prepared water-based emulsion A was subjected to the followingevaluation tests. The results of the tests are shown in Table 1. In astorage stability test, the water-based emulsion A was stored at 50° C.for one month. After the test, the condition of the water-based emulsionA was observed and then classified into "A" (there was no change in thecondition) or "B" (there was a settlement of disperse phase particles).In a mechanical stability test, the water-based emulsion A was stirredwith a stirrer at a rotation rate of 5,000 rpm for 5 min. After thetest, the condition of the water-based emulsion A was observed and thenclassified into "A" (there was no change in the condition) or "B" (therewas an increase of particle diameter of disperse phase).

The aftermentioned water-based emulsions B-E were prepared in the samemanner as that of the water-based emulsion A except that selectivechanges were made as shown in Table 1 in the kind and quantity of themonomers. Furthermore, the water-based emulsions B-E were subjected tothe same evaluation tests as those of the water-based emulsion A.

                  TABLE 1    ______________________________________             Water-based Emulsion             A      B      C        D    E    ______________________________________    Charged    Monomers (mol %)    CTFE       50.0     45.0   40.0   50.0 45.0    VBu        27.0     0      20.0   30.0 --    V-9        10.0     --     15.0   --   30.0    EVE*       --       10.0   --     10.0 10.0    CHVE*      --       28.0   --     --   15.0    HBAE       10.0     --     --     --   --    HBVE*      --       15.0    5.0    5.0 --    ε-CAE*               --       --     15.0    5.0 --    UA          3.0      2.0    5.0   --   --    Solid Matter               19       22     23     20   22    Conc. (%)    Particle   0.18     0.21   0.16   0.23 0.20    Diameter (μm)    Storage    A        A      A      A    A    Stability    Mechanical A        A      A      A    A    Stability    ______________________________________     *EVE: ethyl vinyl ether; CHVE: cyclohexyl vinyl ether; HBVE: hydroxybutyl     vinyl ether; and CAE: caprolactone-modified allyl ether made by DAICEL     CHEMICAL INDUSTRIES CO.

At a second step, a second compound according to the first aspect of thepresent invention was prepared as follows.

At first, as shown in Table 2, a 2-liter stainless steel autoclaveprovided with an electromagnetic stirrer was charged with 400 g (33 mol%) of a polyoxyethylene (PEG-200 (trade name) of SANYO CHEMICALINDUSTRIES, LTD.) which has an average molecular weight of 200 andhydroxyl group at its terminal(s), and 988 g (67 mol %) of an isocyanate(Y-9030 (trade name) of Nippon Unicar Co.) which contains triethoxysilylgroup and is represented by OCN--(CH₂)₃ --Si--(OEt)₃. Then, the gasatmosphere in the autoclave was replaced by nitrogen gas, and thisoperation was repeated three times. Then, the reaction was carried outat 100° C. for 5 hr, thereby to prepare the second compound A. The ¹H-NMR measurement was conducted for identifying the reaction product andfor determining the yield. In this measurement, particular peaks at 4.2ppm and 5.1 ppm, suggesting that urethane bond was formed by thereaction, were observed. The yield was determined by the integral ratioof ¹ H-NMR spectrum peaks. The result is shown in Table 2.

The aftermentioned second compounds B-C were respectively prepared inthe same manner as that of the second compound A except that selectivechanges were made as shown in Table 2 in the kind and quantity of theraw materials. After the reactions to obtain the second compounds B-C,xylene used as a solvent was removed by distillation under reducedpressure.

                  TABLE 2    ______________________________________                Second Compounds                A        B        C    ______________________________________    Charged Compounds    (mol % (g))    PEG-200       33 (400)   --       --    NEWCOL-1105*  --         50 (609) 50 (609)    Y-5187*       --         --       50 (307)    Y-9030        67 (988)   50 (370) --    xylene        --         30 (370) 30 (393)    Yield (%)     93         92       92    ______________________________________     *NEWCOL-1105: nonion surfactant; and Y5187 (trade name):     trimethoxysilylcontaining isocyanate of Nippon Unicar Co.

As shown in Table 3, 1 part by weight of a self-emulsifiablepolyisocyanate, BAYHYDUR TPLS-2032 (trade name) of Sumitomo BayerUrethane Co., which has oxyethylene group and isocyanate group in themolecules was mixed with 0.33 parts by weight of the second compound Aobtained by the second step, thereby to prepare a hardener A.

Similarly, each of the aftermentioned hardeners B-E was prepared bymixing a self-emulsifiable polyisocyanate with a second compound, asshown in Table 3.

                  TABLE 3    ______________________________________                 Hardeners                 A     B       C      D    E    ______________________________________    Self-emulsifiable    Polyisocyanates    BAYHYDUR TPLS-2032                   1       --      --   1    1    DC-3901        --      1       1    --   --    Second Compounds    A              0.33    --      --   1.1  --    B              --      0.25    --   --   --    C              --      --      0.4  --   --    Polyisocyanate/Second                   0.33    0.25    0.4  1.1  --    Compounds    ______________________________________

At a fourth step, as shown in Table 4, 24 parts by weight of thehardener A obtained by the third step, per 100 parts by weight of thefluorine-containing copolymer A, was added to the water-based emulsion Aobtained by the first step. This mixture was uniformly stirred to obtaina water-based fluorine-containing paint A.

EXAMPLES 2-4

In each of these examples, Example 1 was repeated except that selectivechanges were made as shown in Table 4 in the kind and quantity of thewater-based emulsion and of the hardener and that 0.5 parts by weight ofN,N,N',N'-tetramethyldiaminohexane (amine catalyst) was added to themixture of the water-based emulsion and the hardener to prepare thewater-based fluorine-containing paint.

As is seen from Table 4, the water-based emulsion C of thefluorine-containing copolymer C was used in Example 2; the water-basedemulsion D of the fluorine-containing copolymer D was used in Example 3;and the water-based emulsion A of the fluorine-containing copolymer Awas used in Example 4.

COMPARATIVE EXAMPLES 1-4

In each of these comparative examples, Example 1 was repeated exceptthat selective changes were made as shown in Table 4 in the kind andquantity of the water-based emulsion and of the hardener.

As is seen from Table 4, the water-based emulsion E of thefluorine-containing copolymer E was used in Comparative Example 1 thewater-based emulsion A of the fluorine-containing copolymer A was usedin Comparative Example 2; the water-based emulsion B of thefluorine-containing copolymer B was used in Comparative Example 3; andthe water-based emulsion C of the fluorine-containing copolymer C wasused in Comparative Example 4.

In Comparative Example 1, the hardener was omitted in the paintpreparation (see Table 4), and both of the hydroxyl-containing compoundand the polymerizable carboxyl-containing compound were omitted in thepreparation of the water-based emulsion E (see Table 1). In ComparativeExample 2, the second compound was omitted in the hardener preparation(see Table 3). In Comparative Example 3, the weight ratio of theself-emulsifiable polyisocyanate to the second compound was higher thanthe essential range (0.01-1) of the present invention (see Table 3). InComparative Example 4, the hardener was in an amount greater than theessential range (1-50 parts by weight per 100 parts by weight of thefluorine-containing copolymer) (see Table 4).

EVALUATION TESTS

In each of Examples 1-4 and Comparative Examples 1-4, the followingevaluation tests were conducted on the paint and the coated film. Theresults are shown in Table 4.

In a dispersibility test on the paint, the hardener was added to thewater-based emulsion. Then, this mixture was stirred for ten seconds.Then, the condition of the paint was observed with the naked eye toevaluate dispersibility of the disperse phase thereof. As to the resultsof the dispersibility test, "A" means that the paint was a homogeneousemulsion; "B" means that large particles of the hardener was found in asmall amount; and "C" means that the hardener particles remained in andprecipitated in the emulsion.

The coated film was prepared as follows. The obtained paint was appliedto an aluminum plate having dimensions of 150 mm, 70 mm and 2 mm, with aspray gun. The coated film was cured at ambient temperature for threedays. The thus obtained coated film having a thickness of 50 μm wassubjected to evaluation tests as follows.

In a specular gloss test, the surface gloss of the coated film at 60degrees was measured.

In a rubbing test, a piece of gauze moistened with xylene was rubbedagainst the coated film until 100 reciprocations thereof. Then, thesurface condition of the coated film was examined with the naked eye. Asto the results, "A" means that the surface condition was not changed atall; "B" means that scratches and/or blushing were formed on the coatedfilm surface; and "C" means that the coated film swelled or dissolved.

In a water resistance test, the coated aluminum plate was immersed inwater for two weeks. After that, the coated film condition was examinedwith the naked eye. As to the results, "A" means that the coated filmwas not changed at all; "B" means that a few blisters were generated onthe coated film; "C" means that blisters were generated thereon, or thatthe coated film exfoliated; and "D" means that cracks were generated inthe coated film.

In a stain resistance test, the coated aluminum plate was bent at thecenter line perpendicular to the longer sides to have upper and lowerportions divided by the center line and to have an angle of 135 degreesbetween these portions. Then, the aluminum plate was arranged relativeto the ground surface such that the upper and lower portionsrespectively have 45 and 90 degrees relative to the ground surface andexposed outdoors for 6 months in Kawagoe City, Saitama Prefecture,Japan. After the exposure, the existence of rain streaks on the lowerportion was examined with the naked eye. As to the results, "A" meansthat no rain-streak was on the lower portion; "B" means that rainstreaks were thereon but unobtrusive; and "C" means that rain streakswere thereon and obtrusive.

In a carbon resistance test, a 3% carbon/kerosene solution was droppedon the coated film. Then, the coated film was placed for one day at 20°C. under saturated vapor pressure of water and kerosene and then driedfor two days at 40° C. Then, it was tried to wash off a stains) causedby dropping the solution thereon, in water, using an ultrasonic washer.Then, the surface condition of the coated film was examined by the nakedeye. Then, when the stain still remained thereon, it was tried to wipethe stain off. Then, the surface condition of the coated film was againexamined by the naked eye. As to the results, "A" means that the stainwas almost washed off and then completely wiped off; "B" means that thestain unobtrusively remained but then wiped off; and "C" means that thestain obtrusively remained and was not wiped off.

In a weathering test, an accelerated testing was conducted with asunshine weathermeter for 4,000 hr, and the surface gloss of each coatedfilm at 60 degrees was measured before and after the weathering test toindicate the degree of weatherability by percentage of the retainedgloss.

                  TABLE 4    ______________________________________                                   Com. Com. Com. Com.           Ex. 1                Ex. 2  Ex. 3  Ex. 4                                   Ex. 1                                        Ex. 2                                             Ex. 3                                                  Ex. 4    ______________________________________    Fluorine-con-    taining Copoly-    mers (parts by    weight)    A        100    --     --   100  --   100  --   --    B        --     --     --   --   --   --   100  --    C        --     100    --   --   --   --   --   100    D        --     --     100  --   --   --   --   --    E        --     --     --   --   100  --   --   --    Hardeners    (parts by    weight)    A        24     --     --   5    --   --   --   --    B        --     35     --   --   --   --   --   55    C        --     --     35   --   --   --   --   --    D        --     --     --   --   --   --   42   --    E        --     --     --   --   --   18   --   --    Paint    A      A      A    A    --   C    A    A    Dispersibility    Coated Film    Characteristics    Specular 78     81     80   84   81   80   61   54    Gloss (%)    Rubbing Test             A      A      A    A    C    A    A    A    Water Re-             A      A      A    A    C    B    D    D    sistance Test    Stain Re-             A      A      A    A    C    B    C    C    sistance    Carbon Re-             A      A      A    A    C    B    A    B    sistance Test    Weatherability             93     89     88   91   62   84   58   73    (%)    ______________________________________

The following nonlimitative Examples 5-10 are illustrative of the secondaspect of the present invention, and the following Comparative Examples5-8 are not thereof. In the following, the amount of each monomerexpressed by mol % for preparing the copolymer is based on the totalnumber of moles of all the monomers.

EXAMPLE 5

At a first step, a water-based emulsion according to the presentinvention was prepared as follows.

At first, as shown in Table 1, a 2-liter stainless steel autoclaveprovided with an electromagnetic stirrer was charged with 140 g (40 mol%) of vinyl butyrate (VBu), 24 g (5 mol %) of 10-undecylenic acid (UA),19 g (5 mol %) of allyl acetoacetate (AAA) made by Showa Denko Co., 742g of water, 0.7 g of potassium persulfate, 0.2 g of sodium carbonatedecahydrate, and 4 g of a nonion emulsifying agent, NEWCOL-504 (tradename) of Nippon Nyukazai Co. Then, the gas atmosphere in the autoclavewas replaced by nitrogen gas, and this operation was repeated threetimes. Then, 153 g (50 mol %) of CTFE was introduced into the autoclave.Then, the polymerization reaction was carried out at 50° C. for 22 hr,to produce a fluorine-containing copolymer F. Then, the gas atmospherein the autoclave was removed. After that, the reaction liquid was takenout of the autoclave, and then concentrated thereby to obtain awater-based emulsion F having a solid matter concentration of 48%.

The aftermentioned water-based emulsions G-N were prepared in the samemanner as that of the water-based emulsion F except that selectivechanges were made as shown in Table 5 in the kind and quantity of themonomers.

The thus prepared water-based emulsions F-N were subjected to evaluationtests which are the same as those of Example 1. The results of the testsare shown in Table 5.

                                      TABLE 5    __________________________________________________________________________              Water-based Emulsions              F   G   H   I   J   K   L   M   N    __________________________________________________________________________    Charged Monomers    (g (mol %))    CTFE      153(50)                  137(45)                      153(50)                          122(40)                              153(50)                                  153(50)                                      153(50)                                          153(50)                                              153(50)    VBu       140(40)                  --  35(10)                          105(30)                              149(40)                                  140(40)                                      140(40)                                          140(40)                                              140(40)    V-9       --  --  107(22)                          --  24(5)                                  --  --  --  24(5)    EVE       --  32(17)                      --  --  --  --  --  --  --    CHVE      --  83(25)                      --  60(18)                              --  --  --  --  --    AAA       19(5)                  38(10)                      30(8)                          --  19(5)                                  19(5)                                      19(5)                                          19(5)                                              --    HBAE/DK*  --  --  --  28(5)                              --  --  --  --  --    HBAE      --  --  --  7(2)                              --  --  --  --  --    UA        24(5)                  15(3)                      48(10)                          24(5)                              --  --  --  --  24(5)    HA*       --  --  --  --  --  17(5)                                      --  --  --    ODA*      --  --  --  --  --  --  36(5)                                          --  --    HBVE/CA   --  --  --  --  --  --  --  27(5)                                              --    Particle Diameter (μm)              0.20                  0.18                      0.14                          0.23                              0.32                                  0.24                                      0.20                                          0.21                                              0.20    Storage Stability              A   A   A   A   A   C   A   A   A    Mechanical Stability              A   A   A   A   C   C   C   A   A    __________________________________________________________________________     *HBAE/DK: polymerizable ally compound prepared by reacting hydroxylbutyl     allyl ether with diketone; HA: 6heptenoic acid; and ODA: 17octadecylenic     acid.

At a second step, a hardener aqueous solution containing 12 wt % ofadipic acid dihydrazide made by Otsuka chemical Co. was added to thewater-based emulsion F, in an amount as shown in Table 6, thereby toobtain a one-package type water-based fluorine-containing paint.

                                      TABLE 6    __________________________________________________________________________                                   Com.                                      Com.                                         Com.                                            Com.               Ex. 5                  Ex. 6                     Ex. 7                        Ex. 8                            Ex. 9                               Ex. 10                                   Ex. 5                                      Ex. 6                                         Ex. 7                                            Ex. 8    __________________________________________________________________________    Fluorine-containing    Copolymers    (parts by weight)    F          100                  100                     -- --  -- --  -- -- -- --    G          -- -- 100                        --  -- --  -- -- -- --    H          -- -- -- 100 -- --  -- -- -- --    I          -- -- -- --  100                               100 -- -- -- --    J          -- -- -- --  -- --  100                                      -- -- --    L          -- -- -- --  -- --  -- 100                                         -- --    M          -- -- -- --  -- --  -- -- 100                                            --    N          -- -- -- --  -- --  -- -- -- 100    Hardeners    (parts by weight)    Adipic Acid               5  -- 3  --  -- 5   5  5  -- 5    Dihydrazide    APA-L      -- 7  -- 5   5  --  -- -- 5  --    Coated Film    Characteristics    Specular Gloss (%)               80 76 81 80  81 79  81 82 83 85    Rubbing Test               A  A  A  A   A  A   B  B  A  C    Water Resistance Test               A  A  A  A   A  A   A  C  A  C    Stain Resistance               A  A  A  A   A  A   C  B  B  C    Carbon Resistance Test               A  A  A  A   A  A   B  B  B  C    Weatherability (%)               91 92 90 90  91 93  65 58 53 47    __________________________________________________________________________

EXAMPLES 6-9

In each of these examples, Example 5 was repeated except that selectivechanges were made as shown in Table 6 in the kind and quantity of thewater-based emulsion and of the hardener, to prepare the water-basedfluorine-containing paint.

In Examples 6 and 8-9, as shown in Table 6, a polymer having hydrazinogroup at its side chain, APA-L (trade name) of Otsuka Chemical Co., wasdissolved in water, thereby to prepare a 12 wt % APA-L aqueous solution.This solution was used as a hardener aqueous solution.

In Examples 6-9, as shown in Table 6, the fluorine-containing copolymersF-I and the water-based emulsions F-I were respectively used.

EXAMPLE 10

At first, a titanium oxide paste containing 72% of titanium oxidedispersed in water was added to the water-based emulsion I, in an amountof 25 parts by weight of the titanium oxide paste per 100 parts byweight of the fluorine-containing copolymer I. Then, 2 parts by weightof an aqueous solution containing 3% of hydroxyethyl cellulose(thickener), METHOLLOSE (trade name) of Shin-Etsu Chemical Co., wasadded to the mixture, thereby to obtain a white-color enamel. Then, 5parts by weight of an adipic acid dihydrazide aqueous solution as thatof Example 5, per 100 parts by weight of the fluorine-containingcopolymer I, was added to the enamel, thereby to obtain a one-packagetype water-based fluorine-containing white paint.

COMPARATIVE EXAMPLES 5-8

In each of these comparative examples, Example 5 was repeated exceptthat selective changes were made as shown in Table 6 in the kind andquantity of the water-based emulsion and of the hardener.

In Comparative Examples 5-8, as shown in Table 6, thefluorine-containing copolymers J, L, M and N and the water-basedemulsions J, L, M and N were respectively used.

In Comparative Example 5, the polymerizable unsaturated carboxylic acidwas omitted in the preparation of the fluorine-containing copolymer J(see Table 5). In Comparative Example 6, the polymerizable unsaturatedcarboxylic acid was replaced by 17-octadecylenic acid which is notaccording to the present invention (see Table 5). In Comparative Example7, the polymerizable unsaturated carboxylic acid was replaced by aproduct (HBVE/CA) prepared by reacting hydroxybutyl vinyl ether withsuccinic anhydride (see Table 5), and there was used a hardener which isthe same as that of Examples 6 and 8-9 (see Table 6). This product,HBVE/CA, is a polymerizable unsaturated carboxylic acid not according tothe present invention. In Comparative Example 8, the polymerizable allycompound was omitted (see Table 5).

EVALUATION TESTS

In each of Examples 5-10 and Comparative Examples 5-8, evaluation testswhich are the same as those of Example 1 were conducted on the coatedfilm, except that the evaluation standard for the stain resistance testwas slightly modified as described hereinafter. The results are shown inTable 6.

The coated film was prepared in the same manner as in Evaluation Testsin Example 1. With this, the obtained coated film had a thickness ofabout 30 μm, a flat surface, and a high transparency in each of Examples5-9; it had a thickness of 47 μm in Example 10; and it had a thicknessof about 35 μm, a flat surface, and a high transparency in each ofComparative Examples 5-8.

In the stain resistance test, after the exposure, the existence of rainstreaks on the lower portion, and the stains on the upper portion wereexamined with the naked eye. As to the results, "A" means that norain-streak was on the lower portion, and the upper portion was hardlystained; "B" means that rain streaks were on the lower portion butunobtrusive, and the upper portion was stained; and "C" means that rainstreaks were on the lower portion and obtrusive, and the upper portionwas greatly stained.

What is claimed is:
 1. A water-based fluorine-containing paintcomprising:a water-based emulsion containing water as a dispersionmedium and a fluorine-containing copolymer as a disperse phase, saidfluorine-containing copolymer being prepared by emulsion polymerizationof 30-65 mol % of a fluoroolefin, 0.1-20 mol % of a polymerizableunsaturated carboxylic acid represented by the general formula (1), 1-30mol % of a polymerizable allyl compound represented by the generalformula (2), and 20-65 mol % of a first compound which is one of a vinylester and a vinyl ether; and a hardener which is a second compoundcontaining in the molecule at least two hydrazino groups,

    CH.sub.2 ═CH--(CH.sub.2).sub.n --COOH                  (1)

where n is an integer from 7 to 9, ##STR3## where R represents--(AO)_(n) -- in which A is an alkylene group having a carbon atomnumber from 2 to 4, and n is an integer from 0 to
 20. 2. A paintaccording to claim 1, wherein said fluoroolefin is one selected from thegroup consisting of chlorotrifluoroethylene, tetrafluoroethylene,hexafluoropropene, hexafluoroisobutene, vinylidene fluoride,trifluoroethylene, and vinyl fluoride.
 3. A paint according to claim 1,wherein said carboxylic acid is one selected from the group consistingof decenoic acid, 10-undecylenic acid, and dodecylenic acid.
 4. A paintaccording to claim 3, wherein said carboxylic acid is said10-undecylenic acid.
 5. A paint according to claim 1, wherein said allylcompound is allyl acetoacetate.
 6. A paint according to claim 1, whereinsaid fluorine-containing copolymer is prepared by emulsionpolymerization.
 7. A paint according to claim 6, wherein an emulsifyingagent is used in said emulsion polymerization and is in an amount ofless than 5 parts by weight per 100 parts by weight of a total of all ofmonomers used in said emulsion polymerization.
 8. A paint according toclaim 6, wherein water is used in said emulsion polymerization and is inan amount from 50 to 400 parts by weight per 100 parts by weight of atotal of all of monomers used in said emulsion polymerization.
 9. Apaint according to claim 1, wherein said hardener is in an amount from 1to 30 parts by weight per 100 parts by weight of saidfluorine-containing copolymer.